...the DNA molecule that packaged into thread-like structures. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure.
I would say to be safe age 11.
"glazed"
Glazing is the process of covering a ceramic piece with glass allowing it to hold liquid (and food) without leaking. when left a small part of the ceramic not glazed allows the pottery piece to be fired in a kiln without exploding.